Application-Specific Integrated Circuits (ASICs), including Very Large Scale Integration (VLSI) chips typically draw power from external sources such as grid power (mains), batteries or the like. Increasingly, however, devices utilizing such components demand greater levels of energy efficiency. This is largely due to the prevalence of wireless and mobile devices with convenience items becoming more widespread.
Personal communication devices, such as mobile phones, PDAs, handheld PCs and the like, as well as many entertainment devices, such as media players, MP3, MP4, mobile DVD, digital cameras and the like, as well as other household, office and leisure gadgets are commonly powered by batteries of electrochemical power cells. A drawback with battery operated devices is that electrochemical power cells often run out of power at inconvenient times and therefore batteries need to be regularly recharged or replaced.
Such devices may be less dependent upon power provided by electrochemical power cells if some of their components were able to power themselves. Thus, the energy efficiency of mobile devices may be improved by a convenient and effective solar powered VLSI chip. Furthermore, such solar powered components could be effectively used in applications where a power supply is unavailable. Self-powering components may therefore be utilized in a variety of stand-alone communication units, road signs for remote locations, in buoys, floats or other maritime applications.
Although attempts have been made to connect VLSI chips to photovoltaic cells (PVs) in order that they might draw solar power therefrom, the chips and photovoltaic cells are generally manufactured separately and later connected together using external wiring, gates, contacts or terminals. For example, U.S. Pat. No. 6,680,468 to Wang, titled, “Electrical-supply-free MOS integrated circuit”, describes an electrical-supply-free MOS integrated circuit comprising: a semiconductor device having a current terminal, an input voltage terminal, and a common terminal. The voltage difference between the input voltage terminal and the common terminal controls current flow through the current terminal. An opto-electronic device is also provided to convert incident light into an electrical signal. In another example, PCT Application Publication No. WO 03079438 to Gidon, et al. titled, “Multijunction Photovoltaic Device with Shadow-free Independent Cells and the Production Method Thereof”, describes a multijunction photovoltaic device with independent cells. Contact pick-ups are provided on the front and/or rear face of the cells by means of metal wells, the sides of which are insulated from the semi-conducting layers.
Furthermore, United States Patent Application No. 20020170591 to Armer, et al., titled “Method and apparatus for powering circuitry with on-chip solar cells within a common substrate”, describes a light-powered transponder. In order to create sufficient voltage differential, two photovoltaic elements are used. The photovoltaic elements generate voltages of different polarities. Despite the inherent difficulties presented by the use of a standard Complementary metal-oxide-semiconductor (CMOS) process, Aimer's system is directed towards achieving a voltage differential sufficient to power an ASIC by using photovoltaic elements independently to generate voltages with different polarities.
As mentioned, all the above-described solutions require separate interconnecting conductors between their integrated circuits and their power sources. Any additional components however compromise the dimensions of the host devices and may provide additional sources of failure. The need remains, therefore, for efficient solar power provision to integrated circuits. Embodiments described herein below address this need.